Human exposure to diesel exhaust induces CYP1A1 expression and AhR activation without a coordinated antioxidant response

BACKGROUND

Diesel exhaust (DE) induces neutrophilia and lymphocytosis in experimentally exposed humans. These responses occur in parallel to nuclear migration of NF-κB and c-Jun, activation of mitogen activated protein kinases and increased production of inflammatory mediators. There remains uncertainty regarding the impact of DE on endogenous antioxidant and xenobiotic defences, mediated by nuclear factor erythroid 2-related factor 2 (Nrf2) and the aryl hydrocarbon receptor (AhR) respectively, and the extent to which cellular antioxidant adaptations protect against the adverse effects of DE.

METHODS

Using immunohistochemistry we investigated the nuclear localization of Nrf2 and AhR in the epithelium of endobronchial mucosal biopsies from healthy subjects six-hours post exposure to DE (PM10, 300 µg/m3) versus post-filtered air in a randomized double blind study, as a marker of activation. Cytoplasmic expression of cytochrome P450s, family 1, subfamily A, polypeptide 1 (CYP1A1) and subfamily B, Polypeptide 1 (CYP1B1) were examined to confirm AhR activation; with the expression of aldo-keto reductases (AKR1A1, AKR1C1 and AKR1C3), epoxide hydrolase and NAD(P)H dehydrogenase quinone 1 (NQO1) also quantified. Inflammatory and oxidative stress markers were examined to contextualize the responses observed.

RESULTS

DE exposure caused an influx of neutrophils to the bronchial airway surface (p = 0.013), as well as increased bronchial submucosal neutrophil (p < 0.001), lymphocyte (p = 0.007) and mast cell (p = 0.002) numbers. In addition, DE exposure enhanced the nuclear translocation of the AhR and increased the CYP1A1 expression in the bronchial epithelium (p = 0.001 and p = 0.028, respectively). Nuclear translocation of AhR was also increased in the submucosal leukocytes (p < 0.001). Epithelial nuclear AhR expression was negatively associated with bronchial submucosal CD3 numbers post DE (r = -0.706, p = 0.002). In contrast, DE did not increase nuclear translocation of Nrf2 and was associated with decreased NQO1 in bronchial epithelial cells (p = 0.02), without affecting CYP1B1, aldo-keto reductases, or epoxide hydrolase protein expression.

CONCLUSION

These in vivo human data confirm earlier cell and animal-based observations of the induction of the AhR and CYP1A1 by diesel exhaust. The induction of phase I xenobiotic response occurred in the absence of the induction of antioxidant or phase II xenobiotic defences at the investigated time point 6 h post-exposures. This suggests DE-associated compounds, such as polycyclic aromatic hydrocarbons (PAHs), may induce acute inflammation and alter detoxification enzymes without concomitant protective cellular adaptations in human airways.

POS0957 THE PREVALENCE AND FACTORS RELATED TO SLEEP APNOEA IN ANKYLOSING SPONDYLITIS

Background:

An increased prevalence of obstructive sleep apnoea (OSA) has been suggested in ankylosing spondylitis (AS), but few controlled studies have been performed.

Objectives:

We thus aimed to study the prevalence of OSA in patients with AS compared to controls and to study if disease-related and non-disease-related factors were determinants of OSA in AS patients.

Methods:

One hundred and fifty-five patients with AS were included in the Backbone study that investigates severity and comorbidities in AS. Controls were recruited from the Swedish CardioPulmonary bioImage Study (SCAPIS). Participants were asked to be examined with a home sleep-monitoring device during one night’s sleep to evaluate the presence of OSA. For each AS patient, 45-70 years, four controls were matched for sex, age, weight and height. OSA was defined as an apnoea-hypopnea-index ≥5 events/hour.

Results:

In total, 63/155(40.6%) patients with AS were examined with a home sleep-monitoring device out of which 46 patients were 45-70 years and therefore matched (mean age 57.2±7.5years, 30(65.2%) men) with 179 controls (mean age 57.2±4.5years, 123(68.7%) men). Twenty-two out of 46(47.8%) patients with AS vs. 91/179(50.8%) controls had OSA, p=0.72. No differences measurements evaluating OSA were noted in AS vs. controls. In logistic regression analysis, based on all 63 examined AS-patients, several AS-related variables were associated with OSA but after adjusting for age and sex, only higher age and BMI, remained to be significant determinants of OSA, Table 1.

Table 1.

Univariable and age- and sex-adjusted logistic regression analyses with obstructive sleep apnoea as dependent variable in 63 patients with ankylosing spondylitis.

VariablesUnivariable logistic regression analyses, Odds Ratio (95%CI)PAge- and sex-adjusted logistic regression analyses,Odds Ratio (95%CI)PSex, male1.9(0.6-5.5)0.251.5(0.4-4.8)0.53Age1.1(1.0-1.2)0.0021.1(1.0-1.2)0.002BMI1.4(1.1-1.7)0.0011.6(1.2- 2.2)0.001Duration of symptoms1.1(1.0-1.1)0.0281.0(0.9-1.1)0.79BASMI1.9(1.3-2.9)0.0021.5(0.9 -2.5)0.87BASFI1.4(1.0-2.0)0.0381.3(0.9-2.0)0.88≥1 Syndesmophyte3.9(1.3-12.2)0.0173.0(0.8-11.3)0.10mSASSS1.0(1.0-1.1)0.0471.0(0.98-1.05)0.25Metabolic syndrome4.3(1.5-12.9)0.0081.4(0.3-6.6)0.69Epworth Sleep Scale1.2(1.0-1-3)0.0231.2(1.0-1.4)0.29

Conclusion:

In this case-control study, patients with AS did not have a higher prevalence of OSA compared to controls. AS patients with OSA had higher BMI and were older compared to patients without OSA.

Disclosure of Interests:

None declared.

New Insight in the Q^{2} Dependence of Proton Generalized Polarizabilities

Virtual Compton scattering on the proton has been investigated at three yet unexplored values of the four-momentum transfer Q^{2}: 0.10, 0.20, and 0.45  GeV^{2}, at the Mainz Microtron. Fits performed using either the low-energy theorem or dispersion relations allowed the extraction of the structure functions P_{LL}-P_{TT}/ε and P_{LT}, as well as the electric and magnetic generalized polarizabilities α_{E1}(Q^{2}) and β_{M1}(Q^{2}). These new results show a smooth and rapid falloff of α_{E1}(Q^{2}), in contrast to previous measurements at Q^{2}=0.33  GeV^{2}, and provide for the first time a precise mapping of β_{M1}(Q^{2}) in the low-Q^{2} region.

Measures of bronchodilator response of FEV1, FVC and SVC in a Swedish general population sample aged 50-64 years, the SCAPIS Pilot Study

BACKGROUND

Data are lacking from general population studies on how to define changes in lung function after bronchodilation. This study aimed to analyze different measures of bronchodilator response of forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC) and slow vital capacity (SVC).

MATERIALS AND METHODS

Data were derived from the Swedish Cardiopulmonary Bioimage Study (SCAPIS) Pilot study. This analysis comprised 1,050 participants aged 50-64 years from the general population. Participants were investigated using a questionnaire, and FEV1, FVC and SVC were recorded before and 15 minutes after inhalation of 400 µg of salbutamol. A bronchodilator response was defined as the relative change from baseline value expressed as the difference in units of percent predicted normal. Predictors of bronchodilator responses were assessed using multiple linear regression models. Airway obstruction was defined as FEV1/FVC ratio below lower limit of normal (LLN) before bronchodilation, and COPD was defined as an FEV1/FVC ratio below LLN after bronchodilation. Physician-diagnosed asthma was defined as an affirmative answer to "Have you ever had asthma diagnosed by a physician?". Asymptomatic never-smokers were defined as those not reporting physician-diagnosed asthma, physician-diagnosed COPD or emphysema, current wheeze or chronic bronchitis and being a lifelong never-smoker.

RESULTS

Among all subjects, the greatest bronchodilator responses (FEV1, FVC and SVC) were found in subjects with asthma or COPD. The upper 95th percentile of bronchodilator responses in asymptomatic never-smokers was 8.7% for FEV1, 4.2% for FVC and 5.0% for SVC. The bronchodilator responses were similar between men and women. In a multiple linear regression model comprising all asymptomatic never-smokers, the bronchodilator response of FEV1 was significantly associated with airway obstruction and height.

CONCLUSION

When the bronchodilator response in asymptomatic never-smokers is reported as the difference in units of predicted normal, significant reversibility of FEV1, FVC and SVC to bronchodilators is ~9%, 4% and 5%, respectively.

Cytotoxic immune responses in the lungs correlate to disease severity in patients with hantavirus infection

Hantavirus infections may cause severe and sometime life-threatening lung failure. The pathogenesis is not fully known and there is an urgent need for effective treatment. We aimed to investigate the association between pulmonary viral load and immune responses, and their relation to disease severity. Bronchoscopy with sampling of bronchoalveolar lavage (BAL) fluid was performed in 17 patients with acute Puumala hantavirus infection and 16 healthy volunteers acting as controls. Lymphocyte subsets, granzyme concentrations, and viral load were determined by flow cytometry, enzyme-linked immunosorbent assay (ELISA), and quantitative reverse transcription polymerase chain reaction (RT-PCR), respectively. Analyses of BAL fluid revealed significantly higher numbers of activated CD8⁺ T cells and natural killer (NK) cells, as well as higher concentrations of the cytotoxins granzymes A and B in hantavirus-infected patients, compared to controls. In patients, Puumala hantavirus RNA was detected in 88 % of BAL cell samples and correlated inversely to the T cell response. The magnitude of the pulmonary cytotoxic lymphocyte response correlated to the severity of disease and systemic organ dysfunction, in terms of need for supplemental oxygen treatment, hypotension, and laboratory data indicating renal failure, cardiac dysfunction, vascular leakage, and cell damage. Regulatory T cell numbers were significantly lower in patients compared to controls, and may reflect inadequate immune regulation during hantavirus infection. Hantavirus infection elicits a pronounced cytotoxic lymphocyte response in the lungs. The magnitude of the immune response was associated with disease severity. These results give insights into the pathogenesis and possibilities for new treatments.

The Swedish CArdioPulmonary BioImage Study: objectives and design

Cardiopulmonary diseases are major causes of death worldwide, but currently recommended strategies for diagnosis and prevention may be outdated because of recent changes in risk factor patterns. The Swedish CArdioPulmonarybioImage Study (SCAPIS) combines the use of new imaging technologies, advances in large-scale 'omics' and epidemiological analyses to extensively characterize a Swedish cohort of 30 000 men and women aged between 50 and 64 years. The information obtained will be used to improve risk prediction of cardiopulmonary diseases and optimize the ability to study disease mechanisms. A comprehensive pilot study in 1111 individuals, which was completed in 2012, demonstrated the feasibility and financial and ethical consequences of SCAPIS. Recruitment to the national, multicentre study has recently started.

Cardiovascular effects of particulate air pollution exposure: time course and underlying mechanisms

Air pollution is now recognized as an important independent risk factor for cardiovascular morbidity and mortality and may be responsible for up to 3 million premature deaths each year worldwide. The mechanisms underlying the observed effects are poorly understood but are likely to be multifactorial. Here, we review the acute and chronic effects of air pollution exposure on the cardiovascular system and discuss how these effects may explain the observed increases in cardiovascular morbidity and mortality.

Comparison of the proteomes of three yeast wild type strains: CEN.PK2, FY1679 and W303

Yeast deletion strains created during gene function analysis projects very often show drastic phenotypic differences depending on the genetic background used. These results indicate the existence of important molecular differences between the CEN.PK2, FY1679 and W303 wild type strains. To characterise these differences we have compared the protein expression levels between CEN.PK2, FY1679 and W303 strains using twodimensional gel electrophoresis and identified selected proteins by mass spectrometric analysis. We have found that FY1679 and W303 strains are more similar to each other than to the CEN.PK2 strain. This study identifies 62 proteins that are differentially expressed between the strains and provides a valuable source of data for the interpretation of yeast mutant phenotypes observed in CEN.PK2, FY1679 and W303 strains.

Ozone exposure enhances mast-cell inflammation in asthmatic airways despite inhaled corticosteroid therapy

Asthmatics are recognised to be more susceptible than healthy individuals to adverse health effects caused by exposure to the common air pollutant ozone. Ozone has been reported to induce airway neutrophilia in mild asthmatics, but little is known about how it affects the airways of asthmatic subjects on inhaled corticosteroids. We hypothesised that ozone exposure would exacerbate the pre-existent asthmatic airway inflammation despite regular inhaled corticosteroid treatment. Therefore, we exposed subjects with persistent asthma on inhaled corticosteroid therapy to 0.2 ppm ozone or filtered air for 2 h, on 2 separate occasions. Lung function was evaluated before and immediately after exposure, while bronchoscopy was performed 18 h post exposure. Compared to filtered air, ozone exposure increased airway resistance. Ozone significantly enhanced neutrophil numbers and myeloperoxidase levels in airway lavages, and induced a fourfold increase in bronchial mucosal mast cell numbers. The present findings indicate that ozone worsened asthmatic airway inflammation and offer a possible biological explanation for the epidemiological findings of increased need for rescue medication and hospitalisation in asthmatic people following exposure to ambient ozone.

The influence of the menstrual cycle, normal pregnancy and pre-eclampsia on platelet activation

Platelet activation has a key role in mediating thrombotic and inflammatory events. This study aimed to determine the influence of the menstrual cycle, pregnancy and pre-eclampsia on in vivo platelet activation. Twelve healthy nulliparous, non-smoking women with regular menses were studied over a single menstrual cycle. Twenty-one healthy primigravida pregnant women were studied longitudinally at 16, 24, 32 and 37 weeks gestation and seven weeks post-partum. Sixteen primigravida women with pre-eclampsia were studied at time of diagnosis and at seven weeks post-partum. Platelet-monocyte aggregates and platelet-surface P-selectin expression were assessed by flow-cytometry. Soluble P-selectin and CD40 ligand (CD40L) were measured by ELISA. Markers of platelet activation did not vary over the menstrual cycle. Platelet-monocyte aggregates were greater in the third trimester of pregnancy compared to non-pregnant women (p=0.003). Platelet surface and plasma soluble P-selectin concentrations increased with gestation (p<0.0001) and were raised by 24 weeks of pregnancy compared to non-pregnant women (p< or =0.02 for both) and together with platelet monocyte aggregates, decreased post-partum (p< or =0.02). Soluble CD40L concentrations fell in pregnancy, reaching a nadir at mid-gestation (p=0.002). There were no differences in markers of platelet activation between normal and pre-eclamptic pregnancies. In conclusion, platelet activation is increased in pregnancy and increases with gestation but is unaffected by pre-eclampsia. This suggests that systemic platelet activation is a feature of pregnancy but this is not affected by established pre-eclampsia.

Reducing inter-replicate variation in fourier transform infrared spectroscopy by extended multiplicative signal correction

Fourier transform infrared (FT-IR) spectroscopy is a powerful tool for characterizing biological tissues and organisms, but it is plagued by replicate variation of various sources. Here, a method for estimating and correcting unwanted replicate variation in multivariate measurement signals, based on extended multiplicative signal correction (EMSC), is presented. Systematic patterns of unwanted methodological variations are estimated from replicate spectra, modeled by a linear subspace model, and implemented into EMSC. The method is applied to FT-IR spectra of two different sets of microorganisms (different double gene knockout strains of Saccharomyces cerevisiae and different species of Listeria) and compared to other preprocessing methods used in FT-IR absorption spectroscopy of microorganisms. The EMSC replicate correction turns out to perform best among the compared methods.

Influence of menstrual cycle on circulating endothelial progenitor cells

BACKGROUND

Endothelial progenitor cells (EPCs) are circulating mononuclear cells that participate in angiogenesis. The aim of this study was to determine the influence of the menstrual cycle on the number and function of EPCs, and to investigate their relationship with circulating concentrations of sex steroids and inflammatory mediators.

METHODS

Ten healthy nulliparous, premenopausal, non-smoking women with regular menses were studied over a single menstrual cycle. Venepuncture was performed in the menstrual, follicular, peri-ovulatory and luteal phases. EPCs were quantified by flow cytometry (CD133(+)CD34(+)KDR(+) phenotype) and the colony-forming unit (CFU-EPC) functional assay. Circulating concentrations of estradiol, progesterone and inflammatory mediators (TNF-alpha, IL-6, sICAM-1 and VEGF) were measured by immunoassays.

RESULTS

The numbers of CD133(+)CD34(+)KDR(+) cells were higher in the follicular phase (0.99 +/- 0.3 x 10(6) cells/l) compared with the peri-ovulatory phase (0.29 +/- 0.1 x 10(6) cells/l; P < 0.05). In contrast, the numbers of CFU-EPCs did not vary over the menstrual cycle. There were no correlations between EPCs and concentrations of either circulating sex steroids or inflammatory mediators.

CONCLUSIONS

CD133(+)CD34(+)KDR(+) cells but not CFU-EPCs vary during the menstrual cycle. Our findings suggest a potential role for circulating EPCs in the normal cycle of physiological angiogenesis and repair of the uterine endometrium that is independent of circulating sex steroids or inflammatory mediators.

Diesel exhaust exposure enhances the ozone-induced airway inflammation in healthy humans

Exposure to particulate matter and ozone cause adverse airway reactions. Individual pollutant effects are often addressed separately, despite coexisting in ambient air. The present investigation was performed to study the effects of sequential exposures to diesel exhaust (DE) and ozone on airway inflammation in human subjects. Healthy subjects underwent bronchoscopy with bronchoalveolar lavage (BAL) and bronchial wash (BW) sampling on two occasions. Once following a DE exposure (with 300 mug.m(-3) particles with a 50% cut-off aerodynamic diameter of 10 mum) with subsequent exposure to O(3) (0.2 ppm) 5 h later. The other bronchoscopy was performed after a filtered air exposure followed by an ozone exposure, using an identical protocol. Bronchoscopy was performed 24 h after the start of the initial exposure. Significant increases in neutrophil and macrophage numbers were found in BW after DE followed by ozone exposure versus air followed by ozone exposure. DE pre-exposure also raised eosinophil protein X levels in BAL compared with air. The present study indicates additive effects of diesel exhaust on the ozone-induced airway inflammation. Together with similar results from a recent study with sequential diesel exhaust and ozone exposures, the present data stress a need to consider the interaction and cumulative effects of different air pollutants.

Lower airways inflammation in allergic rhinitics: a comparison with asthmatics and normal controls

BACKGROUND

Allergic rhinitis (AR) and asthma represent a continuum of atopic disease. AR is believed to pre-dispose an individual to asthma. Compared with asthmatics and normal controls, the inflammatory response in the lower airways of rhinitics is not fully elucidated. To test the hypothesis that the inflammatory response in the airways of subjects with AR is at a level intermediate between that in normal controls and asthmatics, we have characterized bronchial inflammation and cytokine mRNA levels in non-asthmatic allergic rhinitics and compared it with subjects with allergic asthma and with normal controls.

METHODS

Endobronchial mucosal biopsies were obtained at bronchoscopy from 14 allergic rhinitics, 16 asthmatics and 21 normal controls. Biopsies were embedded into glycol methacrylate resin for immunohistochemical analysis of cellular inflammation and snap frozen for semi-quantitative PCR analysis of cytokine mRNA levels.

RESULTS

Airway inflammation in rhinitic subjects was characterized by an increase in submucosal eosinophils, mast cells and the mRNA expression of TNF-alpha, at an intermediate level between healthy and asthmatics. In addition, CD3(+) and CD8(+) lymphocytes in the epithelium, the endothelial expression of vascular adhesion molecule-1 and IL-1 beta mRNA were higher in the allergic rhinitics compared with both normal controls and asthmatics, whereas growth-related oncogene alpha-mRNA was decreased in AR compared with both healthy and asthmatics. Airway inflammation in the asthmatic group was characterized by higher numbers of eosinophils and mast cells, together with an increase in TNF-alpha-mRNA compared with both healthy and rhinitics. IFN-gamma mRNA was the highest in normal controls and lowest in the asthmatics.

CONCLUSIONS

In individuals with AR the present data suggest an intermediate state of airway inflammation between that observed in normal individuals and subjects with clinical asthma. It is also indicated that IFN-gamma production by CD8(+) T lymphocytes could be protective against the development of airway hyperresponsiveness. Further work is needed to evaluate this hypothesis.

Road tunnel air pollution induces bronchoalveolar inflammation in healthy subjects

Traffic-related air pollution is associated with adverse respiratory effects. The aim of the present study was to investigate whether exposure to air pollution in a road tunnel causes airway inflammatory and blood coagulation responses. A total of 16 healthy subjects underwent bronchoscopy with bronchial mucosal biopsies and bronchoalveolar lavage (BAL) on two occasions, in random order: once at 14 h after a 2-h exposure to air pollution in a busy road tunnel, and once after a control day with subjects exposed to urban air during normal activities. Peripheral blood was sampled prior to bronchoscopy. The road tunnel exposures included particulate matter with a 50% cut-off aerodynamic diameter of 2.5 microm, particulate matter with a 50% cut-off aerodynamic diameter of 10 mum and nitrogen dioxide which had median concentrations of 64, 176 and 230 microg.m(-3), respectively. Significantly higher numbers of BAL fluid total cell number, lymphocytes and alveolar macrophages were present after road tunnel exposure versus control. Significantly higher nuclear expression of the transcription factor component c-Jun was found in the bronchial epithelium after exposure. No upregulation of adhesion molecules or cellular infiltration was present and blood coagulation factors were unaffected. In conclusion, exposure of healthy subjects to traffic-related air pollution resulted in a lower airway inflammatory response with cell migration, together with signs of an initiated signal transduction in the bronchial epithelium.

Airway antioxidant and inflammatory responses to diesel exhaust exposure in healthy humans

Pulmonary cells exposed to diesel exhaust (DE) particles in vitro respond in a hierarchical fashion with protective antioxidant responses predominating at low doses and inflammation and injury only occurring at higher concentrations. In the present study, the authors examined whether similar responses occurred in vivo, specifically whether antioxidants were upregulated following a low-dose DE challenge and investigated how these responses related to the development of airway inflammation at different levels of the respiratory tract where particle dose varies markedly. A total of 15 volunteers were exposed to DE (100 microg x m(-3) airborne particulate matter with a diameter of <10 microm for 2 h) and air in a double-blinded, randomised fashion. At 18 h post-exposure, bronchoscopy was performed with lavage and mucosal biopsies taken to assess airway redox and inflammatory status. Following DE exposure, the current authors observed an increase in bronchial mucosa neutrophil and mast cell numbers, as well as increased neutrophil numbers, interleukin-8 and myeloperoxidase concentrations in bronchial lavage. No inflammatory responses were seen in the alveolar compartment, but both reduced glutathione and urate concentrations were increased following diesel exposure. In conclusion, the lung inflammatory response to diesel exhaust is compartmentalised, related to differing antioxidant responses in the conducting airway and alveolar regions.

Airway inflammation in iron ore miners exposed to dust and diesel exhaust

The aim of the present study was to investigate if underground miners exposed to dust and diesel exhaust in an iron ore mine would show signs of airway inflammation as reflected in induced sputum. In total, 22 miners were studied, once after a holiday of at least 2 weeks and the second time after 3 months of regular work. Control subjects were 21 "white-collar" workers. All subjects completed a questionnaire regarding medical and occupational history, and underwent lung function testing and induced sputum collection. Total and differential cell counts and analyses of the fluid phase of the induced sputum were performed. Sampling of personal exposure to elemental carbon, nitrogen dioxide and inhalable dust was recorded. The average concentrations of inhalable dust, nitrogen dioxide and elemental carbon were 3.2 mg.m-3, 0.28 mg.m-3 and 27 microg.m-3, respectively. Miners had increased numbers of inflammatory cells, mainly alveolar macrophages and neutrophils, and increased concentrations of fibronectin, metalloproteinase-9 and interleukin-10 in induced sputum compared with controls. In conclusion, miners in an underground iron ore mine demonstrated persistent airway inflammation that was as pronounced after a 4-week holiday as after a 3-month period of work underground in the mine.

Increased expression of p38 MAPK in human bronchial epithelium after lipopolysaccharide exposure

Bacterial endotoxin (lipopolysaccharides (LPS)) is normally present in the wall of Gram-negative bacteria and has potent pro-inflammatory properties. Exposure to LPS has been shown to induce neutrophilic airway inflammation in humans. The aim of this investigation was to study the early inflammatory responses to LPS exposure in human airway mucosa in vivo. In total, 15 healthy nonsmoking volunteers participated. Bronchoscopy was performed on two separate occasions, 3 h after saline inhalation and after inhalation of 50 mug LPS in saline. Endobronchial mucosal biopsy specimens were taken and stained immunohistochemically using a panel of monoclonal antibodies directed against mitogen-activated protein kinases (MAPKs), transcription factors, cytokines, adhesion molecules and inflammatory cells. Expression of p38 MAPK increased as a consequence of LPS exposure, as determined by both total epithelial staining and nuclear location. These two responses were strongly associated. Epithelial expression of interleukin-8 showed a tendency towards a significant increase after LPS compared to saline. Epithelial mast cell numbers were increased after LPS, whereas neutrophil numbers were unchanged. Inhalation of lipopolysaccharide induced activation of the bronchial epithelium, as demonstrated 3 h after exposure by increased expression of p38 mitogen-activated protein kinase and interleukin-8, and may represent early regulatory steps in the subsequent development of a neutrophilic bronchial inflammation.

Different airway inflammatory responses in asthmatic and healthy humans exposed to diesel

Particulate matter (PM) pollution adversely affects the airways, with asthmatic subjects thought to be especially sensitive. The authors hypothesised that exposure to diesel exhaust (DE), a major source of PM, would induce airway neutrophilia in healthy subjects, and that either these responses would be exaggerated in subjects with mild allergic asthma, or DE would exacerbate pre-existent allergic airways. Healthy and mild asthmatic subjects were exposed for 2 h to ambient levels of DE (particles with a 50% cut-off aerodynamic diameter of 10 microm (PM10) 108 microg x m(-3)) and lung function and airway inflammation were assessed. Both groups showed an increase in airway resistance of similar magnitude after DE exposure. Healthy subjects developed airway inflammation 6 h after DE exposure, with airways neutrophilia and lymphocytosis together with an increase in interleukin-8 (IL-8) protein in lavage fluid, increased IL-8 messenger ribonucleic acid expression in the bronchial mucosa and upregulation of the endothelial adhesion molecules. In asthmatic subjects, DE exposure did not induce a neutrophilic response or exacerbate their pre-existing eosinophilic airway inflammation. Epithelial staining for the cytokine IL-10 was increased after DE in the asthmatic group. Differential effects on the airways of healthy subjects and asthmatics of particles with a 50% cut-off aerodynamic diameter of 10 microm at concentrations below current World Health Organisation air quality standards have been observed in this study. Further work is required to elucidate the significance of these differential responses.

Clara cell protein as a biomarker for ozone-induced lung injury in humans

Exposure to ozone (O3) impairs lung function, induces airway inflammation and alters epithelial permeability. Whilst impaired lung function and neutrophilia have been observed at relatively low concentrations, altered lung epithelial permeability is only seen after high-dose challenges. The appearance of Clara cell protein (CC16) in serum has been proposed as a sensitive marker of lung epithelial injury. Here, the use of CC16 as an injury biomarker was evaluated under a controlled exposure to O3 and the relationship between this marker of lung injury and early lung function decrements was investigated. Subjects (n=22) were exposed on two separate occasions to 0.2 parts per million O3 and filtered air for 2 h. Blood samples were drawn and lung function assessed at 2 h pre-exposure, immediately before and immediately after exposure as well as 2 and 4 h postexposure. O3 increased CC16 serum concentrations at 2 h (12.0+/-4.5 versus 8.4+/-3.1 microg x L(-1)) and 4 h postexposure (11.7+/-5.0 versus 7.9+/-2.6 microg x L(-1)) compared with air concentrations. Archived samples from O3 studies utilising the same design indicated that this increase was sustained for up to 6 h postexposure (9.1+/-2.6 versus 7.1+/-1.7 microg x L(-1)) with concentrations returning to baseline by 18 h (7.7+/-2.9 versus 6.6+/-1.7 microg x L(-1)). In these studies, the increased plasma CC16 concentration was noted in the absence of increases in traditional markers of epithelial permeability. No association was observed between increased CC16 concentrations and lung function changes. To conclude, Clara cell protein represents a sensitive and noninvasive biomarker for ozone-induced lung epithelial damage that may have important uses in assessing the health effects of air pollutants in future epidemiological and field studies.

Repeated daily exposure to 2 ppm nitrogen dioxide upregulates the expression of IL-5, IL-10, IL-13, and ICAM-1 in the bronchial epithelium of healthy human airways

BACKGROUND

Repeated daily exposure of healthy human subjects to NO2 induces an acute airway inflammatory response characterised by neutrophil influx in the bronchial mucosa

AIMS

To assess the expression of NF-kappaB, cytokines, and ICAM-1 in the bronchial epithelium.

METHODS

Twelve healthy, young non-smoking volunteers were exposed to 2 ppm of NO2/filtered air (four hours/day) for four successive days on separate occasions. Fibreoptic bronchoscopy was performed one hour after air and final NO2 exposures. Bronchial biopsy specimens were immunostained for NF-kappaB, TNF-alpha, eotaxin, Gro-alpha, GM-CSF, IL-5, -6, -8, -10, -13, and ICAM-1 and their expression was quantified using computerised image analysis.

RESULTS

Expression of IL-5, IL-10, IL-13, and ICAM-1 increased following NO2 exposure.

CONCLUSION

Upregulation of the Th2 cytokines suggests that repeated exposure to NO2 has the potential to exert a "pro-allergic" effect on the bronchial epithelium. Upregulation of ICAM-1 highlights an underlying mechanism for leucocyte influx, and could also explain the predisposition to respiratory tract viral infections following NO2 exposure since ICAM-1 is a major receptor for rhino and respiratory syncytial viruses.

Ozone-induced bronchial epithelial cytokine expression differs between healthy and asthmatic subjects

BACKGROUND

Ozone (O3) is a common air pollutant associated with adverse health effects. Asthmatics have been suggested to be a particularly sensitive group.

OBJECTIVE

This study evaluated whether bronchial epithelial cytokine expression would differ between healthy and allergic asthmatics after ozone exposure, representing an explanatory model for differences in susceptibility.

METHODS

Healthy and mild allergic asthmatic subjects (using only inhaled beta2-agonists prn) were exposed for 2 h in blinded and randomized sequence to 0.2 ppm of O3 and filtered air. Bronchoscopy with bronchial mucosal biopsies was performed 6 h after exposure. Biopsies were embedded in GMA and stained with mAbs for epithelial expression of IL-4, IL-5, IL-6, IL-8, IL-10, TNF-alpha, GRO-alpha, granulocyte-macrophage colony-stimulating factor (GM-CSF), fractalkine and ENA-78.

RESULTS

When comparing the two groups at baseline, the asthmatic subjects showed a significantly higher expression of IL-4 and IL-5. After O3 exposure the epithelial expression of IL-5, GM-CSF, ENA-78 and IL-8 increased significantly in asthmatics, as compared to healthy subjects.

CONCLUSION

The present study confirms a difference in epithelial cytokine expression between mild atopic asthmatics and healthy controls, as well as a differential epithelial cytokine response to O3. This O3-induced upregulation of T helper type 2 (Th2)-related cytokines and neutrophil chemoattractants shown in the asthmatic group may contribute to a subsequent worsening of the airway inflammation, and help to explain their differential sensitivity to O3 pollution episodes.

Effect of ozone on bronchial mucosal inflammation in asthmatic and healthy subjects

Epidemiological studies suggestthat asthmatics are more affected by ozone than healthy people. This study tested three hypotheses (1) that short-term exposure to ozone induces inflammatory cell increases and up-regulation of vascular adhesion molecules in airway lavages and bronchial tissue 6 h after ozone exposure in healthy subjects; (2) these responses are exaggerated in subjects with mild allergic asthma; (3) ozone exacerbates pre-existent allergic airways inflammation. We exposed 15 mild asthmatic and 15 healthy subjects to 0.2 ppm of ozone or filtered air for 2 h on two separate occasions. Airway lavages and bronchial biopsies were obtained 6 h post-challenge. We found that ozone induced similar increases in bronchial wash neutrophils in both groups, although the neutrophil increase in the asthmatic group was on top of an elevated baseline. In healthy subjects, ozone exposure increased the expression of the vascular endothelial adhesion molecules P-selectin and ICAM- 1, as well as increasing tissue neutrophil and mast cell numbers. The asthmatics showed allergic airways inflammation at baseline but ozone did not aggravate this at the investigated time point. At 6 h post-ozone-exposure, we found no evidence that mild asthmatics were more responsive than healthy to ozone in terms of exaggerated neutrophil recruitment or exacerbation of pre-existing allergic inflammation. Further work is needed to assess the possibility of a difference in time kinetics between healthy and asthmatic subjects in their response to ozone.

Fermentative capacity after cold storage of baker's yeast is dependent on the initial physiological state but not correlated to the levels of glycolytic enzymes

Growth and starvation of baker's yeast was monitored by on-line microcalorimetry and cells originating from four different physiological states were stored at low temperature (4 degrees C) for up to 26 days. The different physiological states were designated F (respiro-Fermentative phase of growth), R (initial Respiratory phase of growth), -N (non-growing state because of Nitrogen depletion), and -NC (non-growing state because of both Nitrogen and Carbon depletion). The cells were tested before and after cold storage for their fermentative capacity, and characterised by 2D gel analysis (and subsequent quantitative silver staining and image analysis with software PDQUEST) for their levels of six enzymes of the glycolytic pathway (hexokinase 2 (Hxk2p), fructose bisphosphate aldolase (Fba1p), glyceraldehyde-3-phosphate dehydrogenase (Tdh3p), enolase A (Enolp), enolase B (Eno2p), and triose phosphate isomerase (Tpi1p)) and two enzymes of the fermentative branch (pyruvate decarboxylase (Pdc1p) and alcohol dehydrogenase (Adh1p)). The enzymes Hxk2p, Tdh3p, Eno2p, Pdc1p and Adh1p were down-regulated by 25-80% during the transition between the F and R states. During the transition to non-growing states (-N and -NC states), the levels of Hxk2p, Tdh3p and Eno2p were further reduced. However, after cold storage, the glycolytic and fermentative enzymes of the different physiological states were expressed to the same extent. In contrast, the fermentative capacity differed between the states; the R-state cells were superior compared to cells from the other states tested and preserved more than 50% of their initial fermentative capacity (6 mmol ethanol per gram dry weight and hour). Our data therefore clearly demonstrate that persistence of fermentative capacity during total starvation at low temperature after as long as 1 month is strongly dependent on the physiological state from which the cells originate. However, the level of expression of the glycolytic enzymes could not explain the difference in fermentative capacity of the different physiological states after cold storage.

The catabolic capacity of Saccharomyces cerevisiae is preserved to a higher extent during carbon compared to nitrogen starvation

A comparison of catabolic capacity was made between S. cerevisiae cells subjected to 24 h carbon or nitrogen starvation. The cells were shifted to starvation conditions at the onset of respiratory growth on ethanol in aerobic batch cultures, using glucose as the carbon and energy source. The results showed that the catabolic capacity was preserved to a much larger extent during carbon compared to nitrogen starvation. Nitrogen starvation experiments were made in the presence of ethanol (not glucose) to exclude the effect of glucose transport inactivation (Busturia and Lagunas, 1986). Hence, the difference in catabolic capacity could not be attributed to differences in glucose transport capacity during these conditions. In order to understand the reason for this difference in starvation response, measurement of protein composition, adenine nucleotides, inorganic phosphate, polyphosphate and storage carbohydrates were performed. No clear correlation between any of these variables and catabolic capacity after starvation could be obtained. However, there was a positive correlation between total catabolic activity and intracellular ATP concentration when glucose was added to starved cells. The possible mechanism for this correlation, as well as what determines the ATP level, is discussed.

Differences in basal airway antioxidant concentrations are not predictive of individual responsiveness to ozone: a comparison of healthy and mild asthmatic subjects

The air pollutant ozone induces both airway inflammation and restrictions in lung function. These responses have been proposed to arise as a consequence of the oxidizing nature of ozone, depleting endogenous antioxidant defenses with ensuing tissue injury. In this study we examined the impact of an environmentally relevant ozone challenge on the antioxidant defenses present at the surface of the lung in two groups known to have profound differences in their antioxidant defense network: healthy control (HC) and mild asthmatic (MA) subjects. We hypothesized that baseline differences in antioxidant concentrations within the respiratory tract lining fluid (RTLF), as well as induced responses, would predict the magnitude of individual responsiveness. We observed a significant loss of ascorbate (ASC) from proximal (-45.1%, p <.01) and distal RTLFs (-11.7%, p <.05) in healthy subjects 6 h after the end of the ozone challenge. This was associated (Rs, -0.71, p <.01) with increased glutathione disulphide (GSSG) in these compartments (p =.01 and p <.05). Corresponding responses were not seen in asthmatics, where basal ASC concentrations were significantly lower (p <.01) and associated with elevated concentrations of GSSG (p <.05). In neither group was any evidence of lipid oxidation seen following ozone. Despite differences in antioxidant levels and response, the magnitude of ozone-induced neutrophilia (+20.6%, p <.01 [HC] vs. +15.2%, p =.01 [MA]) and decrements in FEV(1) (-8.0%, p <.01 [HC] vs. -3.2%, p <.05 [MA]) did not differ between the two groups. These data demonstrate significant differences between the interaction of ozone with RTLF antioxidants in MA and HC subjects. These responses and variations in basal antioxidant defense were not, however, useful predictive markers of group or individual responsiveness to ozone.

An improved gas distribution system for anaerobic screening of multiple microbial cultures

A cultivation set-up for multiple cultures has been designed that can be used for anaerobic screening for quantitative changes in growth rate or other analyses, e.g. protein composition of different strains. The developed gas distribution system provides a reproducible level of anaerobicity in 30 cultivation flasks and resembles the open system of a high-performance bioreactor in that it ensures cultivation at atmospheric pressure and avoids supersaturation of carbon dioxide. The system is cheap and user-friendly and allows rapid screenings of many strains simultaneously.

Identification of nuclei associated proteins by 2D-gel electrophoresis and mass spectrometry

In clinical neuroscience as well as in many other clinical disciplines, the completion of the human genome project offers a new possibility to identify and localize the products of the genes, the proteins. Nuclear proteins are synthesized in the cytoplasm and imported into the nucleus by multiple pathways. The mechanisms by which nuclear accumulation of different molecular species occur are unclear but it is apparent that changes in the cellular and molecular events associated with the accumulation of nuclear proteins sometimes precedes transformation of cells into diseased states. The significance of the accumulation and the operation of nuclear proteins remain to be elucidated in detail. Such knowledge will play a key role in the understanding of the regulation of transcription and its disturbances in several of our most devastating diseases. In this paper we present a strategy to identify nuclear associated proteins in small samples by using two-dimensional electrophoresis and mass spectrometry. We have used human blood lymphocytes as a model, but the method should be rather general for any kind of tissue. Twenty two proteins were randomly chosen, and of these 18 proteins were identified by database searching of mass spectrometric data, obtained from in-gel tryptic digests of the spots. Thirteen proteins recently described with nuclear localization and function were identified, and five proteins; calgranulin B, glyceraldehyde-3-phosphate dehydrogenase (G3P2), a TATA-binding protein (ATBP), tubulin beta chain and moesin were also identified as being nuclear associated. The presented data clearly shows of the great role of two-dimensional gel electrophoresis and modern mass spectrometry in the excavation of the protein patterns on the subcellular level, and the ability to use small samples well suited for clinical screening.

Nitric oxide (NO) in exhaled air after experimental ozone exposure in humans

We hypothesized that ozone, a common air pollutant, potent in producing airway inflammation, would increase the production of exhaled nitric oxide (NO). If so, measurement of exhaled NO could potentially be a valuable tool in population studies of air pollution effects. Eleven healthy non-smoking volunteers were exposed to 0.2 ppm ozone (O3) and filtered air for 2h on two separate occasions. Exhaled NO and nasal NO were measured before and on five occasions following the exposures. Changes in exhaled and nasal NO after ozone exposure were adjusted for changes after air exposure. There was a slight decrease in exhaled NO (-0.6; -3.1-1.2 ppb) (median and 95% confidence interval) and of nasal NO (-57; -173-75 ppb) directly after the ozone exposure. No significant changes in exhaled or nasal NO were however found 6 or 24 h after the exposure. Within the examined group, an O3 exposure level proven to induce an airway inflammation caused no significant changes in exhaled or nasal NO levels. Hence, the current study did not yield support for exhaled NO as a useful marker of ozone-induced oxidative stress and airway inflammation after a single exposure. This contrasts with data for workers exposed to repeated high peaks of ozone. The potential for exhaled NO as a marker of oxidative stress therefore deserves to be further elucidated.

Health effects of diesel exhaust emissions

Epidemiological studies have demonstrated an association between different levels of air pollution and various health outcomes including mortality, exacerbation of asthma, chronic bronchitis, respiratory tract infections, ischaemic heart disease and stroke. Of the motor vehicle generated air pollutants, diesel exhaust particles account for a highly significant percentage of the particles emitted in many towns and cities. This review is therefore focused on the health effects of diesel exhaust, and especially the particular matter components. Acute effects of diesel exhaust exposure include irritation of the nose and eyes, lung function changes, respiratory changes, headache, fatigue and nausea. Chronic exposures are associated with cough, sputum production and lung function decrements. In addition to symptoms, exposure studies in healthy humans have documented a number of profound inflammatory changes in the airways, notably, before changes in pulmonary function can be detected. It is likely that such effects may be even more detrimental in asthmatics and other subjects with compromised pulmonary function. There are also observations supporting the hypothesis that diesel exhaust is one important factor contributing to the allergy pandemic. For example, in many experimental systems, diesel exhaust particles can be shown to act as adjuvants to allergen and hence increase the sensitization response. Much of the research on adverse effects of diesel exhaust, both in vivo and in vitro, has however been conducted in animals. Questions remain concerning the relevance of exposure levels and whether findings in such models can be extrapolated into humans. It is therefore imperative to further assess acute and chronic effects of diesel exhaust in mechanistic studies with careful consideration of exposure levels. Whenever possible and ethically justified, studies should be carried out in humans.

Rap1p-binding sites in the saccharomyces cerevisiae GPD1 promoter are involved in its response to NaCl

Mechanisms involved in transcriptional regulation of the osmotically controlled GPD1 gene in Saccharomyces cerevisiae were investigated by promoter analysis. The GPD1 gene encodes NAD(+)-dependent glycerol-3-phosphate dehydrogenase, a key enzyme in the production of the compatible solute glycerol. By analysis of promoter deletions, we identified a region at nucleotides -478 to -324, in relation to start of translation, to be of great importance for both basal activity and osmotic induction of GPD1. Electrophoretic mobility shift and DNase I footprint analyses demonstrated protein binding to parts of this region that contain three consensus sequences for Rap1p (repressor activator protein 1)-binding sites. Actual binding of Rap1p to this region was confirmed by demonstrating enhanced electrophoretic mobility of the protein-DNA complex with extracts containing an N-terminally truncated version of Rap1p. The detected Rap1p-DNA interactions were not affected by changes in the osmolarity of the growth medium. Specific inactivation of the Rap1p-binding sites by a C-to-A point mutation in the core of the consensus showed that this factor is a major determinant of GPD1 expression since mutations in all three putative binding sites for Rap1p strongly hampered osmotic induction and drastically lowered basal activity. We also show that the Rap1p-binding sites appear functionally distinct; the most distal site (core of the consensus at position -386) exhibited the highest affinity for Rap1p and was strictly required for low salt induction (< or =0.6 m NaCl), but not for the response at higher salinities (> or =0.8 m NaCl). This indicates tha different molecular mechanisms might be operational for low and high salt responses of the GPD1 promoter.

Airway inflammation following exposure to diesel exhaust: a study of time kinetics using induced sputum

The adverse health effects of particulate matter pollution are of increasing concern. In a recent bronchoscopic study in healthy volunteers, pronounced airway inflammation was detected following exposure to diesel exhaust (DE). The present study was conducted in order to evaluate the time kinetics of the inflammatory response following exposure to DE using induced sputum from healthy volunteers. Fifteen healthy nonsmoking volunteers were exposed to DE particles with a 50% cut-off aerodynamic diameter of 10 microm 300 microg x m(-3) and air for 1 h on two separate occasions. Sputum induction with hypertonic saline was performed 6 and 24 h after each exposure. Analyses of sputum differential cell counts and soluble protein concentrations were performed. Six hours after exposure to DE, a significant increase was found in the percentage of sputum neutrophils (37.7 versus 26.2% p=0.002) together with increases in the concentrations of interleukin-6 (12.0 versus 6.3 pg x mL(-1), p=0.006) and methylhistamine (0.11 versus 0.12 microg x L(-1), p=0.024). Irrespective of exposure, a significant increase was found in the percentage of sputum neutrophils at 24 as compared to 6 h, indicating that the procedure of sputum induction itself may change the composition of sputum. This study demonstrates that exposure to diesel exhaust induces inflammatory response in healthy human airways, represented by an early increase in interleukin-6 and methylhistamine concentration and the percentage of neutrophils. Induced sputum provides a safe tool for the investigation of the inflammatory effects of diesel exhaust, but care must be taken when interpreting results from repeated sputum inductions.

Acute exposure to diesel exhaust increases IL-8 and GRO-alpha production in healthy human airways

We have previously demonstrated that short-term exposure to diesel exhaust (DE) for 1 h induced a marked leukocytic infiltration in the airways of healthy human volunteers involving neutrophils, lymphocytes, and mast cells along with increases in several inflammatory mediators. We hypothesized that the leukocyte infiltration and the various inflammatory responses induced by DE were mediated by enhanced chemokine and cytokine production by resident cells of the airway tissue and lumen. To investigate this, 15 healthy human volunteers were exposed to diluted DE and air on two separate occasions for 1 h each in an exposure chamber. Fiberoptic bronchoscopy was performed 6 h after each exposure to obtain endobronchial biopsies and bronchial wash (BW) cells. Using reverse transcriptase/polymerase chain reaction enzyme-linked immunosorbent assay (RT-PCR ELISA), a novel and sensitive technique to quantify relative amounts of cytokine mRNA gene transcripts, and immunohistochemical staining with computer-assisted image analysis to quantify expression of cytokine protein in the bronchial tissue, we have demonstrated that DE enhanced gene transcription of interleukin-8 (IL-8) in the bronchial tissue and BW cells along with increases in IL-8 and growth-regulated oncogene-alpha (GRO-alpha) protein expression in the bronchial epithelium, and an accompanying trend toward an increase in IL-5 mRNA gene transcripts in the bronchial tissue. There were no significant changes in the gene transcript levels of interleukin-1B (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), interferon gamma (IFN-gamma), and granulocyte macrophage colony-stimulating factor (GM-CSF) either in the bronchial tissue or BW cells after DE exposure at this time point. These observations suggest an underlying mechanism for DE-induced airway leukocyte infiltration and offer a possible explanation for the association observed between ambient levels of particulate matter and various respiratory health outcome indices noted in epidemiological studies.

The level of cAMP-dependent protein kinase A activity strongly affects osmotolerance and osmo-instigated gene expression changes in Saccharomyces cerevisiae

The influence of cAMP-dependent protein kinase (PKA) on protein expression during exponential growth under osmotic stress was studied by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The responses of isogenic strains (tpk2Deltatpk3Delta) with either constitutively low (tpk1(w1)), regulated (TPK1) or constitutively high (TPK1bcy1Delta) PKA activity were compared. The activity of cAMP-dependent protein kinase (PKA) was shown to be a major determinant of osmotic shock tolerance. Proteins with increased expression during growth under sodium chloride stress could be grouped into three classes with respect to PKA activity, with the glycerol metabolic proteins GPD1, GPP2 and DAK1 standing out as independent of PKA. The other osmotically induced proteins displayed a variable dependence on PKA activity; fully PKA-dependent genes were TPS1 and GCY1, partly PKA-dependent genes were ENO1, TDH1, ALD3 and CTT1. The proteins repressed by osmotic stress also fell into distinct classes of PKA-dependency. Ymr116c was PKA-independent, while Pgi1p, Sam1p, Gdh1p and Vma1p were fully PKA-dependent. Hxk2p, Pdc1p, Ssb1p, Met6p, Atp2p and Hsp60p displayed a partially PKA-dependent repression. The promotors of all induced PKA-dependent genes have STRE sites in their promotors suggestive of a mechanism acting via Msn2/4p. The mechanisms governing the expression of the other classes are unknown. From the protein expression data we conclude that a low PKA activity causes a protein expression resembling that of osmotically stressed cells, and furthermore makes cells tolerant to this type of stress.

Metabolic surprises in Saccharomyces cerevisiae during adaptation to saline conditions: questions, some answers and a model

This review describes the metabolic alterations and adaptations of yeast cells in response to osmotic stress. The basic theme of the cellular response is known to be exclusion of the extracellular stress agent salt and intracellular accumulation of the compatible solute glycerol. Molecular details of these basic processes are currently rather well known. However, analysis of expression changes during adaptation to salt has revealed a number of metabolic surprises. These include the induced expression of genes involved in glycerol dissimilation as well as trehalose turnover. The physiological rationale for these responses to osmotic stress is discussed. A model is presented in which it is hypothesised that the two pathways function as glycolytic safety valves during adaptation to stress.

Identification and specificities of N-terminal acetyltransferases from Saccharomyces cerevisiae

N-terminal acetylation can occur cotranslationally on the initiator methionine residue or on the penultimate residue if the methionine is cleaved. We investigated the three N-terminal acetyltransferases (NATs), Ard1p/Nat1p, Nat3p and Mak3p. Ard1p and Mak3p are significantly related to each other by amino acid sequence, as is Nat3p, which was uncovered in this study using programming alignment procedures. Mutants deleted in any one of these NAT genes were viable, but some exhibited diminished mating efficiency and reduced growth at 37 degrees C, and on glycerol and NaCl-containing media. The three NATs had the following substrate specificities as determined in vivo by examining acetylation of 14 altered forms of iso-1-cytochrome c and 55 abundant normal proteins in each of the deleted strains: Ard1p/Nat1p, subclasses with Ser-, Ala-, Gly- and Thr-termini; Nat3p, Met-Glu- and Met-Asp- and a subclass of Met-Asn-termini; and Mak3p subclasses with Met-Ile- and Met-Leu-termini. In addition, a special subclass of substrates with Ser-Glu- Phe-, Ala-Glu-Phe- and Gly-Glu-Phe-termini required all three NATs for acetylation.

Altered lung antioxidant status in patients with mild asthma

Lung lining fluid ascorbic acid (vitamin C) and alpha-tocopherol (vitamin E) concentrations are low in patients with mild asthma even though blood levels are normal or increased. These findings, along with the presence of increased amounts of oxidised glutathione in their airways, indicate that patients with asthma are subject to increased oxidative stress.

Bronchoalveolar inflammation after exposure to diesel exhaust: comparison between unfiltered and particle trap filtered exhaust

OBJECTIVES

Air pollution particulates have been identified as having adverse effects on respiratory health. The present study was undertaken to further clarify the effects of diesel exhaust on bronchoalveolar cells and soluble components in normal healthy subjects. The study was also designed to evaluate whether a ceramic particle trap at the end of the tail pipe, from an idling engine, would reduce indices of airway inflammation.

METHODS

The study comprised three exposures in all 10 healthy never smoking subjects; air, diluted diesel exhaust, and diluted diesel exhaust filtered with a ceramic particle trap. The exposures were given for 1 hour in randomised order about 3 weeks apart. The diesel exhaust exposure apperatus has previously been carefully developed and evaluated. Bronchoalveolar lavage was performed 24 hours after exposures and the lavage fluids from the bronchial and bronchoalveolar region were analysed for cells and soluble components.

RESULTS

The particle trap reduced the mean steady state number of particles by 50%, but the concentrations of the other measured compounds were almost unchanged. It was found that diesel exhaust caused an increase in neutrophils in airway lavage, together with an adverse influence on the phagocytosis by alveolar macrophages in vitro. Furthermore, the diesel exhaust was found to be able to induce a migration of alveolar macrophages into the airspaces, together with reduction in CD3+CD25+ cells. (CD = cluster of differentiation) The use of the specific ceramic particle trap at the end of the tail pipe was not sufficient to completely abolish these effects when interacting with the exhaust from an idling vehicle.

CONCLUSIONS

The current study showed that exposure to diesel exhaust may induce neutrophil and alveolar macrophage recruitment into the airways and suppress alveolar macrophage function. The particle trap did not cause significant reduction of effects induced by diesel exhaust compared with unfiltered diesel exhaust. Further studies are warranted to evaluate more efficient treatment devices to reduce adverse reactions to diesel exhaust in the airways.

Antioxidant consumption and repletion kinetics in nasal lavage fluid following exposure of healthy human volunteers to ozone

To obtain information on the real-time events occurring within human respiratory tract lining fluids (RTLFs) during ozone exposure, sequential nasal lavage was performed on 13 human volunteers exposed on separate occasions to 0.2 parts per million O3 and filtered air (2-h exposures, with intermittent exercise). Nasal lavage was performed and blood samples obtained at four time points throughout each exposure: pre-exposure (Pre-E), 1 h into exposure (1h-E), immediately post-exposure (0h-PE) and 1 h post-exposure (1h-PE). Endobronchial mucosal biopsies were obtained at 1.5 h-post exposure (1.5h-PE). Nasal RTLF neutrophilia was not apparent during, or 1.5 h after, 03 exposure. Furthermore, activation of the pre-existing neutrophil population did not occur. Airway permeability was not altered by this 03 exposure regimen. Sequential lavage resulted in significant washout of RTLF ascorbic acid, reduced glutathione, extracellular superoxide dismutase and myeloperoxidase at 1h-E, 0h-PE and 1.5h-PE relative to baseline Pre-E values. In contrast, RTLF uric acid (UA), total protein and albumin concentrations did not display washout kinetics. Of the antioxidants examined, only UA was clearly depleted by 03, concentrations, falling by 6.22 micromol x L(-1) at 1h-E, compared with 1.61 micromol x L(-1) (p<0.01) during control air exposure. The establishment of a new pseudo-steady-state concentration of RTLF UA (70% of Pre-E values) during the second hour of O3 exposure was coincident with a small but significant increase in plasma UA concentration (19.27 (O3) versus 1.95 micromol x L(-1) (air), p<0.05). These data demonstrate that inhalation of 0.2 parts per million 03 results in the depletion of nasal respiratory tract lining fluid uric acid and that this regional loss of uric acid leads to a small increase in plasma uric acid concentration. Whilst the reaction of uric acid with inspired 03 may confer protection locally, the role of upper airway uric acid as a sink for inhaled O3 is not supported by these findings.

Ozone-induced lung function decrements do not correlate with early airway inflammatory or antioxidant responses

This study sought to clarify the early events occurring within the airways of healthy human subjects performing moderate intermittent exercise following ozone challenge. Thirteen healthy nonsmoking subjects were exposed in a single blinded, crossover control fashion to 0.2 parts per million (ppm) O3 and filtered air for 2 h, using a standard intermittent exercise and rest protocol. Lung function was assessed pre- and immediately post-exposure. Bronchoscopy was performed with endobronchial mucosal biopsies, bronchial wash (BW) and bronchoalveolar lavage (BAL) 1.5 h after the end of the exposure period. Respiratory tract lining fluid (RTLF) redox status was assessed by measuring a range of antioxidants and oxidative damage markers in BW and BAL fluid samples. There was a significant upregulation after O3 exposure in the expression of vascular endothelial P-selectin (p<0.005) and intercellular adhesion molecule-1 (p<0.005). This was associated with a 2-fold increase in submucosal mast cells (p<0.005) in biopsy samples, without evidence of neutrophilic inflammation, and a decrease in BAL fluid macrophage numbers (1.6-fold, p<0.005), with an activation of the remaining macrophage subset (2.5-fold increase in % human leukocyte antigen (HLA)-DR+ cells, p<0.005). In addition, exposure led to a 4.5-fold and 3.1-fold increase of reduced glutathione (GSH) concentrations, in BW and BAL fluid respectively (p<0.05), with alterations in urate and alpha-tocopherol plasma/RTLF partitioning ratios (p<0.05). Spirometry showed reductions in forced vital capacity (p<0.05) and forced expiratory volume in one second (p<0.01), with evidence of small airway narrowing using forced expiratory flow values (p<0.005). Evidence was found of O3-induced early adhesion molecule upregulation, increased submucosal mast cell numbers and alterations to the respiratory tract lining fluid redox status. No clear relationship was demonstrable between changes in these early markers and the lung function decrements observed. The results therefore indicate that the initial lung function decrements are not predictive of, or causally related to the O3-induced inflammatory events in normal human subjects.

Quantitative aspects of the use of bacterial chloramphenicol acetyltransferase as a reporter system in the yeast Saccharomyces cerevisiae

The quantitative aspects of the use of the reporter system chloramphenicol acetyltransferase (CAT) has been evaluated in the yeast Saccharomyces cerevisiae. It was found that the CAT activity measured with a radiosotopic fluor diffusion assay was strongly dependent on the amount of yeast extract applied, both when CAT was expressed endogenously and when a purified Escherichia coli enzyme was investigated. Desalting the yeast extract by gel filtration partly eliminated the problem, indicating that some low-molecular-weight compound was involved in the phenomenon. However, the extract still exhibited stability problems on ice. An immunological CAT assay was tested and found to yield satisfactory quantitative result.

Interleukin-5 production by human airway epithelial cells

Interleukin (IL)-5 is a pleiotropic cytokine that exhibits biologic activity on cells of diverse hemopoieitic lineages. IL-5 enhances mediator release from human basophils and plays a pivotal role in the chemoattraction, proliferation, differentiation, survival, and activation of eosinophils. Th2- and Tc2-like T cells, mast cells, basophils, and eosinophils are the known cellular sources of this cytokine. Using a sensitive and novel reverse transcription-polymerase chain reaction enzyme-linked immunosorbent assay system, we found that IL-5 messenger RNA (mRNA) was constitutively expressed in bronchial biopsies obtained from healthy individuals, and that the levels of IL-5 mRNA expression decreased 1. 5 h after exposure to 0.12 ppm ozone for 2 h. Because the oxidative effects of ozone are confined to the epithelial cell surface and it is known that ozone induces epithelial damage and shedding, we hypothesized that epithelial cells might be a source of IL-5 mRNA. We demonstrate here that both transformed human bronchial epithelial cell lines (A549 and 16HBE14o-) and primary human bronchial and nasal epithelial cells grown in culture constitutively express IL-5 mRNA, which is upregulated on stimulation with tumor necrosis factor (TNF)-alpha. Culture supernatants derived from A549 cells exposed to TNF-alpha and interferon-gamma demonstrated detectable levels of IL-5 protein, and immunostaining of bronchial biopsies obtained from healthy human airways revealed the presence of IL-5 protein localized to the bronchial epithelium. To our knowledge, this is the first report demonstrating IL-5 production by human airway epithelial cells. This observation provides further evidence for the role of airway epithelium in regulating airway immune responses, in particular enhancing chemotaxis, activation, and survival of eosinophils, which could play an important role in the pathogenesis of bronchial asthma.

Thiamine repression and pyruvate decarboxylase autoregulation independently control the expression of the Saccharomyces cerevisiae PDC5 gene

The Saccharomyces cerevisiae gene PDC5 encodes the minor isoform of pyruvate decarboxylase (Pdc). In this work we show that expression of PDC5 but not that of PDC1, which encodes the major isoform, is repressed by thiamine. Hence, under thiamine limitation both PDC1 and PDC5 are expressed. PDC5 also becomes strongly expressed in a pdc1delta mutant. Two-dimensional gel electrophoresis of whole protein extracts shows that thiamine limitation stimulates the production of THI gene products and of Pdc5p. Deletion of PDC1 only stimulates production of Pdc5p. We conclude that the stimulation of PDC5 expression in a pdc1delta mutant is not due to a response to thiamine limitation.